Why are there Spooky Stuff items in the seasons trailer? DLC for a DLC? Again?

For that matter... I am curious: A neat idea would be auto-shifting decorations. As I said I am NOT into micro-managing at all; have never EVER used the holliday stuff or the spooky decorations because quite frankly having to manually add and delete a ton of deco all the time is BOOOOOOOOORING (yes, that many "o"s).

If we could "mark" an area for a a decoration, which then shifted depending on season...? I would love that.